510 VITAMIN Bi2 



Meanwhile a close relationship had become evident between the anti- 

 pernicious anemia factor of concentrated liver extracts and the factor 

 needed by chicks on vegetable diets. The evidence was as follows: 



1. The chick factor ("animal protein factor") had points of similarity to 

 factor X, needed by rats, which was also present in crude animal proteins 

 and absent from vegetable proteins. Furthermore, deficiencies of either 

 factor X in rats or the animal protein factor in chicks were intensified by 

 depleting the maternal supply or by raising the level of vegetable protein 

 in the basal diet. In 1946, it was shown by Gary et al}^ that concentrated 

 injectable liver extract, 15 U.S.P. units per cubic centimeter, was a highly 

 potent source of factor X and that by precipitation with ammonium sulfate 

 a fraction could be prepared from the extract which was effective in amounts 

 of a few micrograms. Ammonium sulfate had been reported to precipitate 

 the anti-pernicious anemia f actor.''' 



TABLE XX 



Activity of Anti-Pernicious Anemia Preparations in Chicks" 



Basal diet: Corn, soybean meal, wheat bran, wheat middlings, casein, alfalfa meal, 



minerals, and pure vitamins 



Average weight 

 Experiment Supplement at 4 weeks 



1 None 219 



1 3% Lederle liver powder 259 



1 0.1 ml. Reticulogen (Lilly) daily by mouth 262 



2 None 209 

 2 0.05 ml. Reticulogen daily by intramuscular injection 301 



2. Anti-pernicious anemia liver extracts were found to be good sources 

 of the animal protein factor in tests with chicks (Table XX). 



In the spring of 1948, the crystallization of the anti-pernicious anemia 

 factor (vitamin B12) from liver was reported.'^' '^ The vitamin was soon 

 found to have biological properties corresponding to those which had been 

 previously established for concentrates of the animal protein factor. 



It was reported in July 1948 that remission in pernicious anemia was 

 produced by injecting concentrates of the animal protein factor, standard- 



'^ C. A. Cary, A. M. Hartman, L. P. Dryden, and G. D. Likely, Federation Proc. 



5, 128 (1946). 

 '8 H. D. Dakin, C. C. Ungley, and R. West, J. Biol. Chem. 115, 771 (1936). 

 " C. A. Nichol, A. R. Robbiee, W. W. Cravens, and C. A. Elvehjem, /. Biol. Chcm. 



170, 419 (1947). 

 '■"^ J. E. Ford, S. K. Kon, and J. W. G. Porter, Biochem. J. 50, ix (1951). 



18 E. L. Rickes, N. G. Brink, F. R. Koniuszy, T. R. Wood, and K. Folkcrs, Scic7ice 

 107, 396 (1948). 



19 E. Lester Smith, NaUire 161, 638 (1948); 162, 144 (1948). 



